Fuel injection for internal combustion engines



Jfine 6, 1933. K. J. E. HESSELMAN 1,912,367

FUEL INJECTION FOR INTERNAL COMBUSTION ENGINES Filed 001'... 30, 1928 Patented June 6, 1933 UNITED STATES PATENT OFFICIE FUEL INJECTION FOR INTERNAL 'COMBU STlION ENGINES Application fled October 30, 1928, Serial No. 315,957, and in Sweden November 7,1927,

The present invention relates to fuel injection for internal combustion engines, and more particularly relates to the injection of liquid fuel by pump means to internal combustion engines of the type in which control of the quantity of fuel supplied to the engine is effected by varying the time of commencement of the period of fuel injection as the load on the engine varies and maintain h the time of the end of the injection perio constant at all engine loads.

When injecting liquid fuel to internal combustion engines, it is desirable to maintain the character of injection, that is, the velocity characteristics of the flow of fuel to the injection nozzle, substantially uniform with respect to engine speed under dltferent conditions of load on the engine, and it is also desirable to maintain, under all conditionsof engine operation, a certain minimum velocity of flow at the end of the injection period.

In one of its aspects a principal object of the present invention is to provide for fuel injection for engines of the above-mentioned type which will have the desired character sties with respect to flow of fuel to the injection nozzle, and .in another of its aspects the invention has for a principal ob ect the provision of improved pump means for supplying fuel, which means is simple and reliable and which involves the fewest possible parts for effecting the desired type of injection. a

In order to obtain the above general objects and other and more detailed objects of v the invention, as will hereinafter more fully appear, I employ a plunger pump, the plunger of which is actuated by a suitable engine driven part operating in timed relation with respect to the engine cycle, and terminate the period of injection by providing a non-return relief valve adapted to be opened'by direct contact of the pump plunger toward the end of the delivery stroke thereofto suddenly interrupt the effective discharge stroke of the pump plunger. The quantity of fuel delivered by the pump plunger'on each of its discharge strokes is controlled by the provision of an adjustable stop arranged to deterits discharge stroke with respect to the engine cycle, so that the plunger on this stroke may be said to follow a given cycle speed curve. By the provision of a relief valve adapted to be opened by contact of the pump plunger, the time of injection is always tel.- minated at the same point on the cycle speed curve and the termination of the effective discharge stroke of the pump prior to the end of the movement of the pump plunger in the direction of its discharge stroke insures the termination of injection, irrespective of load conditions on the engine, at a timewhen the' pump plunger is moving on its discharge stroke, so that injection of fuel at low velocity toward the end of the injection period is avoided.

By the provision of the adjustable stop for controlling the length of the suction stroke of the pump, variations in load on the engine can be compensated for by varying the quantity of fuel supplied, as with the ordinary throttle valve in the case of engines supplied with gaseous fuel, without altering the speed curve characteristics of the pump plunger for the'portion of its effective discharge stroke through which it operates under any condition of load, and thus uniformity of the characteristics of fuel flow from the pump is maintained under different engine operating conditions. In this connection, it will, of course, be appreciated that while the characteristics of fuel flow will at all times be governed by the character of 9 the cycle speed curve, the absolute velocity of injection will vary with variations in engine speed since the pump plunger is actuated by an engine driven part.

In order to insure the termination of the 93 effective discharge stroke of the plunger at a constant point, the cooperating contact surfaces of the plunger and the relief valve are arranged so that the valve is lifted from its seat at the same point in the plunger st oke 109 regardless of the position of rotation of the plunger in the pump body. This is preferabl effected by arranging the relief valve an the plunger coaxially with'the contact surfaces at the axis of the plunger.

By arranging the pump parts in the above general manner, it will be evident that the desiredcontrol of fuel injection-of the type .desired is effected throuzzh the medium of a single ad'ustable stop which may be controlled eit er manually or by governor) without recourse to the aid of movable levers or other valve regulating means, which would require special packing, for transmitting motion from the pump operating means to the valve or valves for regulating the flow of fuel from the pump. Such re ulation of the relief valve as is required is e ected through the medium of the pump plunger which is itself essential to the apparatus.

For a better understanding of the details of the nature of the invention and the manner in which the several objects thereof are attained, reference may be had to the ensuing description of a suitable, form of apparatus for carrying the invention into effect, taken in conjunction with the accompanying drawing forming a part of this specification.

In the drawing 1 indicates a driving shaft, such as the cam shaft of an internal combustion or explosion engine. A cam 2 carried by this shaft engages a roller 3 mounted on the end of a sliding block or tappet 4 which is movable radially relatively to shaft 1. Said sliding block 4 may, forinstance, be formed as a plunger reciprocating in a cylindrical casin 5 and formed with a reduced end 6 which is guided in a corresponding bore.

7 in the casing 5. Placed around said reduced end 6 within the casing 5 is a spring 8 which tends to move the sliding block 4 towards shaft 1 thereby maintaining the roller 3 in constant engagement with the cum 2 or its hub.

The reduced end 6 which projects through the bore 7 is adapted to operate the plunger of'a fuel pump. The fuel pump comprises a casin 16, a plunger 17, a suction valve 18, and a elivery valve 19. The suction valve and the delivery valve are situated in chan nels 20 and 21, respectively, which are at right angles with respect to the longitudinal axis of the plunger. The pump casing is provided with a removable supplementary piece 22 lying in alinement with the pump plunger. This supplementary piece is'bored the whole of its length and contains a spring operated relief valve 23 adapted to be opened by the plunger 17. It will be observed that the inner end of'p'l'un'gler 17 isnormal to the longitudinal axis of the plunger and that the point of contact between the inner end of the plunger and the relief valve 23 coincides with the axis-of the plunger. From this it will be evident that valve 23 will be lifted from its seat at the same point in the discharge stroke of the plunger regardless of the position of rotation of the plun er about its axis. It will further be evident t at when the inner end of the plunger is in the form of a plane surface normal to the axis of the plunger, it is not essential that the point of contact between the plunger and the valve coincide with the axis ofv the plunger, and that when this point of contact does coincide with the axis, the 'ortions' of the end surface of the plunger ra ially outside of thepoint of contact need not be normal to the axis of the plunger. Valve 23 controls a connection between the pump chamber and the suction pipe 24 which leads from said piece 22. Leading from the suction pipe to the channel 20 at a point thereof behind the suction valve is a by-pass channel 25 which cannot be closed by the valve 23.

It is to be noted that the s rin 26 acting on the valve 23 should be 0 s cient tension to resist the highest pressure on the plunger 17 The delivery valve 19 is shown as representing the fuel injection vvalve of the engine in connection with which the pump is used. To this end the respective portion of the pump casing is shown as inserted in the cylinder wall 27 of the engine and in di rect connection with an injecting nozzle 28.

The valve 23 is arranged to interrupt the deiivery stroke of the pump, before the top of the cam reaches the roller 3, by opening a I connection between the delivery space of the pump and the suction pipe. This will render the top portion of the cam ino rative as regards the fuel injection whereh y the last portion of the fuel is positively prevented from entering at too low velocity.

Control of the quantity of fuel injected is effected, as stated above, by var the moment of beginning of the fuel injection. The means provided to effect this variation comprises, in the embodiment shown, a lever 29 engaging a plate on the plunger 17 to limit the suction stroke of the plunger as effected by the spring 30. The lever 29 may be adjusted, either manually or by means of a governor for the engine. The means provided to effect such adjustment, however, are not shown in the drawing, as they may be of- I well-known design. The pump design illustrated comprises, as shown, few and simple elements and will consequently be cheap in manufacture.

Moreover, it may be. readily inspected and cleaned. For the last-mentioned purpose it is. only required. to release those fastening ntieans, as screws or the like, by which the pump is attached to the engine and unscrew the fuel admission pi whereupon both the pump pro r and t e fuel injecting device will be eely accessible for cleaning purposes or for exchange of parts.

Various modifications may be made without departing from the principle of the invention. For instance the pump may be driven in a different way, as by an eccentric. The stop 29 serving to determine the 0 rative length of the plunger stroke, may of a design different from that shown. The suction and delivery valves of the pump may be designed and arranged in various ways.

What I claim is:

1. The method of supplying ametered variable quantity of liquid fuel to the injection nozzle of an internal combustion engine by the aid of a plunger pump having a relief valve which comprises actuating the plunger during its discharge stroke in fixed timed relation with respect to the engine cycle, varying the length of the suction stroke of the plunger in accordance with variations in load on the engine to meter the quantity of fuel drawn into the pump 'by the plunger and terminating the effective discharge stroke of the plunger by causing the plunger to directly open the relief valve at a fixed point in the stroke of the plunger, whereby injection of fuel is terminated at a fixed point in the engine cycle at all loads on the engine.

2. The method of supplying liquid fuel to the injection nozzle of an internal combustion engine by the aid of a plunger pump having a relief valve which comprises reciprocating the pump plunger in fixed timed relation with respect to the engine cycle, stopping the suction stroke of the plunger at different points in accordance with variations in load on the engine to meter the quantity of fuel drawn into the pump, and causing said plunger to directly open said relief valve at a fixed point in the discharge stroke of the plunger at all loads on the eng ine, whereby injection of fuel is terminated at a fixed point in the engine cycle at all loads on the engine.

3. The method of varying the length of the period of injection of liquid fuel to an internal combustion engine by the aid of a plunger pum which comprises reciprocating the pump 1 plhnger in fixed timed relation with respect to the engine cycle, stopping the suction stroke of the pump plunger at different points in the engine cycle in accordance with variations in load on the engine to meter the quantity of fuel drawn into the pump, terminating the effective discharge stroke of the pump at a fixed point in the engine cycle at all loads on the engine, and relating said fixed point to the engine cycle so that termination of said effective discharge stroke occurs prior to the termination of movement of the pump plunger in discharge direction.

4. In the art of injecting liquid fuel to the cylinder of-an internal combustion engine by the aid of a plunger pump and a rotary engine-driven member for actuating the pump, that improvement which consists in terminating the effective discharge stroke of the pump plunger at all engine loads prior to the termination of movement of the pump plunger in discharge direction and with the engine-driven member in the same position of rotation relative to the pump, and controlling the quantity of fuel to be delivered on any given disc arge stroke of the plunger in order to compensate for variations in the load on the engine by var ing the length of the preceding suction stro e of the plunger.

5. In the art of injecting liquid fuel to the cylinder of an internal combustion engine by the aid of a plunger pump having a relief valve for the pump chamber and a rotary engine-driven member for actuating the pump, that improvement which 'consistsin terminating the effective discharge stroke of the plunger at all engine loads by causing the plunger to directly open the relief valve at a fixed point in the stroke of the plunger beforev the plunger terminates its movement in discharge direction and with the rotary member at a fixed point of rotation relative to the pump, and controlling the quantity of fuel to be delivered on any given discharge stroke of the plunger in order to compensate for variations in the load on the engine by varying the length of the preceding suction stroke of the plunger.

6. In the art of injecting liquid fuel to the cylinder of an internal combustion engine by the aid of a plunger pump, that improvement which consists in causing the plunger to move on its discharge stroke in accordance with a given cycle speed curve, terminating the effective discharge stroke of the plunger regardless of variation in engine loads when the plunger is in a position corresponding to a fixed point on said curve ahead of the point thereon representing the termination of movement of the pump plunger in discharge direction and varying the quantityof fuel supplied by the pump to compensate for varlations in load on the engine by causing initiation of the effective discharge stroke when the pump plunger'is in positions corresponding to different points on said curve which are at different distances ahead of said fixed point. v

7. In the art of injecting liquid fuel to the cylinder of an internal combustion engine by the aid of a plunger pump, that improve ment which consists in causing the plunger to move on its discharge stroke in accordance with a given. cycle speed curve, terminating the efiective discharge stroke of the plunger regardless of variation in engine loads when the plunger is in a position corresponding to a fixed point on said curve ahead of the point thereon representing the termination positions corresponding to on said curve which are at different distances of movement of the pump plunger in discharge direction and varying the quantity of fuel supplied by the pump to compensate for variations in load on the engine by varying the, length of the suction stroke of the plunger to cause initiation of the discharge stroke when the pum; lunger is in i erent points ahead of said fixed point. v

8. A fuel pump for internal combustion engines comprising a body forming a pump chamber, a plunger reciprocable in said body and having an inner end extending into said chamber, valved inlet and discharge conduits communicating with said chamber, a relief valve for said-chamber adapted to be opened by said plunger, said relief valve and the inner end of said plunger having cooperating surfaces for causing the relief valve to opened always at the same-point in the discharge stroke of the plunger, and control means for varying the quantity of fuel delivered by the pump to compensate for vae riations in load on the en e comprising an adjustable part for stopping the plunger at different points in its suction stroke to meter the quantity of fuel to be delivered on the succeeding discharge stroke. t

9. A fuel pump for internal combustion engines comprising a body form ng a pump chamber, a plunger reciprocable m said body and having an inner end extending into said chamber, valved inlet and discharge condu ts communicating with said chamber, a relief valve for said chamber adapted to be opened by said plunger, said relief valve and the inner end of said plunger havin cooperating surfaces for causing the relie valve to be I opened at the same point in the discharge stroke of the plunger irrespective of the position of rotation of the plunger, and control means for varying the quantity of fuel delivered by the pump to compensate f or variations, in load on the engine comprising an adjustable partfor stopping the plunger at different points in its suction stroke toineter the quantity of fuel to be delivered on the succeeding discharge stroke.

10. A fuel pump for internahcombustion engines comprising a body forming a pum chamber, a plunger reciprocable in said body and having an inner end extending into said chamber, valved inlet and discharge conduits communicating with said chamber, a relief valve for said chamber adapted to be opened by abutment therea ainst of the inner end of said plunger, said inner end providing a surface having a contour such that all points of said surface capable of contacting said relief valve lie in a plane normal to the axis of reciprocation of said plunger, and control means for varying the quantity of.

fuel delivered by the pump to compensate for variations in load on the engine comprising an adjustable part for stopping the plunger at different points in its suction stroke to meter the quantity of fuel to be delivered on the succeeding discharge stroke.

11. A fuel pump for internal combustion engines comprising a body forming a pump chamber, a plunger reciprocable in said body and having an inner end extending into said chamber, valved inlet and dischargeconduits communicating with said chamber, a relief valve for said chamber arranged in coaxial ali nment with said plunger and adapted to opened by the inner end of the plunger, and control means for varying the quantity of fuel delivered by the pump to compensate for variations in load on the en-- gine comprising an adjustable part for stopping the plunger at different points in its suction stroke to meter the quantity of fuel to.be delivered on the succeeding discharge stroke.

a 1?. A fuel pump for internal combustion engines comprising a body forming a pump chamber, a plunger having a central longitudinal axis 'freciprocable in said body, said plunger comprising an inner-end extending into said chamber, valved inlet and discharge conduits communicating with said chamber, a relief valve for said chamber, the inner end of said plunger and said valve having surfaces adapted to. contact at said axis upon each dischargestroke of the plunger to open said valve, and control means for varying the quantity of fuel delivered by the pump to compensate for variations in load on the engine comprising an adjustable part for stopping the plunger at different points in its suction stroke to meter the quantity of fuel to'be delivered on the succeeding discharge. stroke. I 13. Apparatus for supplying liquid fuel to internal combustion engines comprising a pump havinga body providing a pump chamber, -a'plun r reciprocable in said body and having an inner end in communication with said chamber, valved inlet and discharge conduits in communication with said chamher, a relief valve for said chamber adapted to be opened by said plunger, said relief valve and the inner end of, said plunger having cooperating surfaces for causing the relief valve to be opened always at the same point in the discharge stroke of the plunger, a rotary engine-driven member for actuating said plunger on its discharge stroke, mechanism including said plunger constitutin motion transmitting means of fixed len E between said member and said relief va ve whereby the aforesaid fixed point in the discharge stroke of the plunger corresponds to a hired position of rotation of said member, and control means for varying the quantity of fuel delivered by the pum to compensate for variations in load on t e engine comprising anadjustable part for stopping the plunger at diiferent points in its suction stroke to meter the quantity of fuel to be delivered on the succeeding discharge stroke.

14. Apparatus for supplying liquid fuel to internal combustion engines comprising a pump having a body providing a pump chamber, a plunger reciprocable in said body and having an inner. end in communication with said chamber, valved inlet and discharge conduits in communication with said chamber,, a relief valve for said chamber adapted to be opened by said plunger, said relief valve and the inner end of said plunger having cooperating surfaces for causing the relief valve to be opened always at the same point in the discharge stroke of the plunger, a rotary engine-driven cam for actuating said plunger on its discharge stroke, a reciprocating motion-transmitting tappet of fixed length between said cam and said plunger for causing said relief valve to be 0 ened always with the cam in the same position of rotation, and control means for varying the quantity of fuel delivered by the pump to compensate for variations in load on the engine comprising an adjustable part for stopping the plunger at different points in its suction stroke to meter the quantity of fuel to be delivered on the succeeding discharge stroke.

15. Apparatus for supplying liquid fuel to internal combustion engines comprising a pump having a body providing a pump chamber, valved inlet and discharge conduits in communication with said chamber, a relief valve for said chamber, a rotary engine-driven member for operating the pump, means for insuring opening of said relief valve at all engine loads with said rotary member in the same position of rotation comprising motion transmitting mechanism of fixed length between said member and said valve and includin a pump plunger having an inner end forme to open the relief valve only at a fixed point in the discharge stroke of the plunger, and control means for varying the quantity of fuel delivered by the pump to compensate for variations in load on the engine comprising an adjustable part for stopping the plunger at difi'erent points in its suction stroke to meter the quantity of fuel to be delivered on the succeeding discharge stroke.

In testimony whereof I ha e signed my name.

KNUT JONAS ELIAS HESSELMAN. 

